FlatList & Ref types (#4002)

## Description

This PR fixes 2 type issues that were reported via private channel:

1. Type 'FlatList' is not generic
2. Type 'Ref<ScrollView>' is not assignable to type
'RefObject<ScrollView | null> | undefined'

## Test plan

`yarn ts-check`

<details>
<summary>Tested on the following code</summary>

```tsx
import React, { forwardRef, useEffect, useRef } from 'react';
import { Text } from 'react-native';
import {
  FlatList,
  GestureHandlerRootView,
  ScrollView,
} from 'react-native-gesture-handler';

interface MyComponentProps {
  title: string;
}

const MyCustomScrollView = forwardRef<ScrollView, MyComponentProps>(
  (props, ref) => {
    return (
      <ScrollView ref={ref} style={{ flex: 1 }}>
        <Text>{props.title}</Text>
      </ScrollView>
    );
  }
);

export default function App() {
  const scrollViewRef = useRef<ScrollView>(null);
  const flatListRef = useRef<FlatList<number>>(null);

  useEffect(() => {
    setTimeout(() => {
      console.log(scrollViewRef, flatListRef);
    }, 1000);
  });

  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <MyCustomScrollView ref={scrollViewRef} title="Hello, World!" />
    </GestureHandlerRootView>
  );
}
```

</details>

Author: m-bert

packages/react-native-gesture-handler/src/v3/components/GestureComponents.tsx

@@ -178,4 +178,4 @@ export const FlatList = ((props) => {
 ) => ReactElement | null;
 
 // eslint-disable-next-line @typescript-eslint/no-redeclare
-export type FlatList = typeof FlatList & RNFlatList;
+export type FlatList<ItemT = any> = typeof FlatList & RNFlatList<ItemT>;

packages/react-native-gesture-handler/src/v3/types/NativeWrapperType.ts

@@ -7,7 +7,7 @@ import {
 } from '../hooks/gestures/native/NativeTypes';
 
 export type WrapperSpecificProperties<T = unknown> = {
-  ref?: React.RefObject<T>;
+  ref?: React.Ref<T>;
   onGestureUpdate_CAN_CAUSE_INFINITE_RERENDER?: (
     gesture: NativeGesture
   ) => void;